Device for implanting electrically isolated occlusion helixes

ABSTRACT

The invention relates to a device for the implantation of occlusion helixes ( 3 ) that can be separated by electrolysis in blood vessels and body cavities, especially aneurysms ( 12 ), said device comprising an insertion aid ( 4 ), at least one occlusion helix ( 3 ) that is distally arranged in relation to the insertion aid ( 4 ) and at least one electrolytically corrodible severance element ( 2 ), with at least one stabilization helix ( 5 ) being arranged between severance element ( 2 ) and occlusion helix ( 3 ) and said stabilization helix ( 5 ) being connected with the occlusion helix ( 3 ) by an electrically isolating adhesion layer ( 7 ) such that the occlusion helix ( 3 ) becomes isolated from the voltage when an electrical voltage is applied to the severance element ( 2 ). In this way, the current density in severance element ( 2 ) is further increased so that, on the one hand, shorter severance times are achieved and, on the other, the connection between the occlusion helix ( 3 ) and one of the stabilization helixes ( 5 ) used to stabilize the implant is significantly simplified compared to the known laser welding method according to prior art.

The invention relates to a device for implanting occlusion helixes thatcan be detached by electrolysis in blood vessels and body cavities,especially aneurysms, said device comprising an insertion aid, at leastone occlusion helix that is distally arranged in relation to theinsertion aid and at least one electrolytically corrodible severanceelement, with at least one stabilization helix being arranged betweenseverance element and occlusion helix.

The use of endovascular techniques for the occlusion of body cavities orvessels such as arteries, veins, fallopian tubes or vascular deformities(for example, vascular aneurysms) is known in the art. In this case, theocclusion helix is usually introduced by means of an endovascular guidewire serving as insertion aid through a catheter into the cavity to beoccluded and deposited therein.

To detach the occlusion helix from the insertion aid various methods areknown from prior art. In particular, the electrolytic severance ofstainless steel wire ends as initially described for electro-coagulationby Thompson et al. as well as McAlister et al. in 1979 has proved itsworth in this context (Radiology 133:335-340, November 1979; AJR132:998-1000, June 1979).

Based on this method European patent publication 0 484 468 as welldescribes a device for the implantation of occlusion helixes involvingthe electrolytically corrodible design of the end of the guide wire atthe connection between the guide wire and the occlusion helix. In thismanner the electrical voltage applied to the occlusion helix serving asan anode for electro-thrombozation is utilized for the simultaneousseverance of the wire end and thus the release of the occlusion helix.

All devices of this nature have the disadvantage in that the guide wireintended for the safe transfer of the implant has to be of comparativelymassive design which means severance of the guide wire end by means ofelectrolysis requires a relatively long period of time. For this reason,WO 03/017852 A1 proposes to design an electrolytically corrodible pointin the form of a severance element as part of the occlusion helixproper. Since these severance elements are subjected to significantlylower bending stresses during the implantation process they may have acorrespondingly smaller diameter resulting in the electrolyticdetachment of the occlusion helix to improve and be carried out morequickly. It has, moreover, been possible in this way to use less stableand more flexible materials for the severance element which additionallyaccelerated and improved the detachment process by means ofelectrolysis.

Furthermore, the application of stabilization helixes is known fromprior art said helixes serve the purpose of connecting the severanceelements with the occlusion helixes. These stabilization elements areintended to stabilize and stiffen the implant and are of a diameter thatis smaller than that of the occlusion helixes so that they can beinserted at least partly into the latter. Moreover, the stabilizationhelixes connected to the severance elements also serve to enlarge thesurface at the end of the severance element in order to improve in thismanner the connectability with respect to the occlusion helix. Theconnection is as a rule established with the help of a laser weldingprocess, however connecting a severance element without stabilizationhelix to the occlusion helix would turn out to be rather difficult dueto the small diameter of the severance element. Although the connectioncould thus be more easily established as a result of the additionallyattached stabilization helix bringing about a correspondingly largersurface, laser welding nevertheless is a very complex and sophisticatedtechnology to be applied so that there is need for a more simpletechnique enabling the stabilization and occlusion helixes to beconnected.

To keep the severance times to a minimum it has been disclosed by priorart publications, for instance U.S. Pat. No. 6,620,152, that the implantbe isolated electrically which apparently increases the disposition ofthe wire section envisaged for electrolytic severance to be morevulnerable to electrolytic corrosion. Isolation in this case may bebrought about either by arranging isolation between the implant and theseverance location or by coating the implant with an isolating layer.

However, this prior-art technique has the disadvantage in that theseverance location of the device described in the cited publication issituated in the guide wire which compared to arranging the severancelocation in the area of the occlusion helix is less beneficial for thereasons stated above and described in sufficient detail in WO 03/017852A1 to which express reference is made here.

Furthermore, no additional stabilization helixes which serve to positionand improve the transition to the occlusion helix have been provided forthe isolated implants known from prior art as referred to above.

Proceeding from what is known from prior-art it is therefore theobjective of the invention to provide a device for the implantation ofocclusion helixes which enables the time span required for electrolyticcorrosion to be further reduced and, what is more, provides also for asimplified connection between stabilization helix and occlusion helix.

According to the invention this objective is achieved by providing adevice for the implantation of occlusion helixes that can be detached byelectrolysis in blood vessels and body cavities, especially aneurysms,said device comprising an insertion aid, at least one occlusion helixthat is distally arranged in relation to the insertion aid and at leastone electrolytically corrodible severance element, with at least onestabilization helix being arranged between severance element andocclusion helix and said stabilization helix being connected with theocclusion helix by an electrically isolating adhesion layer such thatthe occlusion helix becomes isolated from the voltage when an electricalvoltage is applied to the severance element.

Other than the isolations known from prior art the isolation proposed bythe invention is not located between severance location and implant butbetween the individual components of the implant. In this manner twoproblems are resolved simultaneously, that is simplifying the connectionof stabilization and occlusion helix on the one hand and shortening theseverance time on the other. The latter is due to the fact that whenvoltage is applied to the severance element the current density in saidelement increases provided other parts of the implant where electrolyticcorrosion shall not take place are isolated from the voltage so applied.

At the same time, establishing the connection between stabilization andocclusion helix is significantly simplified in comparison to prior-artsolutions usually proposing the use of laser welding techniques. Asproposed by the invention the usual course of action calls for anadhesive being applied to at least that end of the stabilization helixthat is envisaged to be connected to the occlusion helix with saidstabilization helix then being brought in contact with the occlusionhelix. It is to be considered especially advantageous to provide theentire stabilization helix with an electrically isolating coating saidcoating may, in particular, consist of an adhesive layer. Followingthis, one end of the stabilization helix can be brought into contactwith the occlusion helix or partly inserted into the same to establish adurable, isolating connection. As a result of the additional isolationof the stabilization helixes by means of an electrically isolatingcoating any corrosion in the area of the stabilization helix isprevented and the current density in the area of the severance elementincreased further which leads to the severance time being reducedcorrespondingly. If thought expedient, even several stabilizationhelixes fit together may be arranged at the occlusion helix.

It is, moreover, considered expedient to arrange for a securing means tobe run through the lumen of the occlusion helix. Securing means of thisnature offer the advantage that in the event of a wrong placement of theocclusion helix or if too large an occlusion helix has been selected forthe area to be occluded and must then be retracted, possibly completelyretracted into the catheter such retraction process is much safer.Retracting an occlusion helix without securing means involves a risk inthat portions of the helix are pulled apart and elongated due to thetensile or torsional stresses applied and in this way be plasticallydeformed irreversibly. In extreme cases the helix may separate or breakgiving rise to life-threatening embolism.

It is known to provide for such securing means to consist of flexiblepolymer threads. However, especially preferred is a variant that isdescribed in DE 101 18 017 A1 according to which the securing meansconsist of a wire made of a material, particularly a metal, having shapememory properties. In comparison with securing elements made of apolymer material such a metallic securing means offers distinctadvantages with respect to its resistance to torsional or tensilestresses. A securing means made of a metal having shape memoryproperties may also offer characteristics known as “super elasticity” sothat such a securing means or element in its flexible state canwithstand particularly high bending or tension loads without the risk offailing or breaking.

As regards the shape-memory properties of the securing means these maybe due to a thermal or mechanical shape-memory effect. Especially provenmaterials used for this purpose are titanium and nickel containingalloys, in particular an alloy known to those skilled in the art underthe name of Nitinol. Furthermore, alternative materials may be used aswell, for example iron or copper based alloys. The properties of theshape-memory material can be precisely controlled or influenced by aperson skilled in the art in a known manner by selecting exactly thematerial composition required. The diameter of such a wire serving assecuring means typically ranges between 0.03 and 0.05 mm.

Moreover, using a shape-memory material for the securing means is alsoconducive to the impression of a superimposed structure on the occlusionhelix after said helix has been released from the catheter and placed inan aneurysm, for example. It is, basically, of advantage if theocclusion helix forms into such a secondary structure when in theaneurysm, for instance takes on helical coil or basket shape, because inthis way the aneurysm is filled up particularly well to make sure aneffective thrombozation of the aneurysm can be achieved. If thoughtexpedient the occlusion helix itself may be preformed into such asuperimposed structure which it assumes when it is released from thecatheter. It may nevertheless be sufficient, however, if exclusively thesecuring means and not the occlusion helix itself is preformed, providedthe force exerted by the securing means is great enough to also forcethe occlusion helix into the shape predetermined by the securing means.The force exerted by the securing means is brought about due to thesecuring means being liberated and released from the constraint of thesurrounding catheter when placed into the aneurysm and re-transformedreturning to its austenite phase which causes it to assume thepreviously impressed structure. Additionally or alternatively, atemperature induced transformation may be caused as well when, uponbeing released from the catheter, the securing means is subjected to theelevated temperature prevailing in the blood stream.

If only one severance element is provided or in the event of severalseverance elements in the area of the most distally arranged segments ofthe occlusion helix the securing means is expediently arranged betweenstabilization helix and distal front section of the occlusion helix,i.e. at its proximal end it is attached to the stabilization helix andat its distal end to the occlusion helix. To make sure an electricalconnection between stabilization helix and occlusion helix is notestablished via the securing means the connection of the securing meansto the distal front section of the occlusion helix is suitably effectedwith the aid of an adhesion layer which enables the occlusion helix tobe isolated from an electrical voltage applied to the severance element.The connection between stabilization helix and metallic securing meansmay also be made up by means of an adhesion layer or by welding orsoldering methods to suit individual needs. In case an adhesion layer isused the securing means as well is electrically isolated from theseverance element whereas the voltage applied to the severance elementfor the purpose of electrolytic corrosion is also applied to thesecuring means in case welding or soldering techniques are employed. Asdescribed in more detail hereinafter the latter may be beneficial incertain cases.

In order to prevent in the latter case that a current flow occurs whencontact is made between the metallic securing means and the occlusionhelix the securing means should be provided with an electricallyisolating coating similar to the one that can be used for thestabilization helix. Such a coating is all the more useful because itprevents the electrolytic corrosion of the securing means proper andkeeps the current density at the severance element at a high level.

As an alternative to the electrical isolation of the securing means theocclusion helix itself may be provided with an electrically isolatingcoating, at least on the inside of the helix. In this manner as well itis effectively ruled out that a current flow occurs between securingmeans and occlusion helix as soon as both elements contact each other.

Especially preferred are devices according to which the occlusion helixis provided with several spaced electrolytically corrodible severanceelements or devices with several spaced occlusion helixes provided withone electrolytically corrodible severance element each arranged betweenthem. Devices of this type are basically known from WO 01/32085 A1 towhich express reference is made here. In this manner one or severalvariably sized longitudinal sections of the occlusion helix can beseparated by electrolysis and placed in the aneurysm. This enablesocclusion helixes of exactly the right length to be placed into theaneurysm. If necessary, even several sections of the same helix may beseparated one after the other and introduced into the cavity to beoccluded. This is beneficial not only in terms of costs and time butalso serves to further minimize surgery risks. Furthermore, theapplication of this method dispenses with the need to always keep readyand use differently sized occlusion helixes for placement into aneurysmsof different size but instead enables a uniformly sized device to beemployed which makes it possible, as required in each individual case,to introduce differently sized sections of the occlusion helix into theaneurysm.

The application of such occlusion helixes having a plurality ofelectrolytically corrodible locations is based on findings according towhich the specific severance location of the occlusion helix that issituated nearest to the distal end of the catheter is separated byelectrolysis when a current is applied to such a device. This is due tothe fact that on the one hand the electrolytically corrodible locationsin the catheter are isolated from the ionic medium through the catheterand thus are not undergoing electrolysis and, on the other hand, thecurrent density decreases in proximal-distal direction owing to thedistally increasing resistance in the occlusion helix or helixes. As aresult of this, the electrolytically corrodible point which, viewed indistal direction, is closest to the distal end of the catheter issubjected to the most intensive electrolytic process and is thuspreferentially dissolved.

In the event of a device having a plurality of severance elements it isexpedient to arrange in the segments of the occlusion helix locatedbetween the severance elements or in the individual occlusion helixesone securing means each which passes through the lumen of the occlusionhelix. In this manner the placement of variably sizable lengths is atthe same time associated with securing each individual segment arrangedbetween the electrolytically corrodible points such that a maximumdegree of safety is achieved with respect to preventing the occlusionhelixes from being torn off.

According to an especially preferred embodiment the individual severanceelements are connected in an electrically conductive fashion viametallic securing means. As per the aforesaid embodiment the securingmeans, although isolated with respect to the occlusion helix, passes thecurrent on to the next, distally arranged severance element. Thetransition in this case may be effected such that the securing means isdirectly connected with the nearest severance element or in such a waythat the securing means has a conductive connection with an additionalstabilization helix at the distal end of a segment of an occlusion helixor with one of several occlusion helixes arranged in series, again withthe stabilization helix being conductively connected with the severanceelement. Typically, on both ends of the severance elements astabilization helix each is arranged said helix connecting the severanceelement with the respective occlusion helix segments. Preferably, eachindividual securing means runs from the stabilization helix located onthe distal end of a severance element to the nearest distally locatedstabilization helix of the following severance element. In this mannerit is ensured that the individual severance elements are connected in anelectrically conductive manner via the stabilization helixes and thesecuring elements attached to said helixes such that an appliedelectrical voltage intended to separate the occlusion helixes istransferred to the individual severance elements. At the same time eachindividual occlusion helix segment is isolated electrically from thestabilization helix because said segment being attached to thestabilization helix with the aid of an electrically isolating adhesionlayer. Basically, the metallic securing means may also be secured to theseverance elements proper and in this manner make sure the flow ofcurrent is established. Only with the most distally arranged occlusionhelix segment does the securing means preferably run up to the distalfront section of the occlusion helix proper where the securing means isconnected with the distal front section via an adhesion layer isolatingthe occlusion helix from the electrical voltage applied with a view tobringing about electrolytic corrosion.

In addition, the securing means is preferably provided with anelectrically isolating coating so that electric current in fact flows indistal direction through the interior of the securing means but neitheran electrolytic corrosion nor electrical contact with the occlusionhelix will occur in this area. As a result of the measures describedabove a very elegant method is provided for the creation of variablyseparable occlusion helixes and, moreover, also the current density atthe severance element is kept particularly low leading to the severancetimes being correspondingly reduced. Furthermore, this embodiment offersmanufacturing advantageous as a connection brought about by adhesionlayers is easier made up than by means of the laser welding techniquesknown from prior art.

For the build-up of the adhesion layers and electrically isolatingcoatings on the securing means and/or stabilization helixes a variety ofmaterials are considered suitable on principle. An important factor tobe observed in this context is naturally the compatibility with and,evenly significant, the approval for medical applications.

Aside from bio-compatibility and isolating properties the hardenabilityof the adhesive is also of advantage, with adhesives that can behardened by radiation, e.g. UV-hardenable adhesives, offering particularbenefits because the radiation introduced to harden the material will,as the case may be, have also a sterilizing effect. The use of acrylateadhesives is considered to be particularly expedient although,basically, other adhesives having the aforesaid characteristics aresimilarly suitable.

Especially preferred is the use of a material commercially availableunder the tradename of “Permabond”, said material being approved andhaving excellently proved its worth in the medical field. Permabond 4L25marketed by National Starche & Chemical Company (ICI) is a UV-hardenableadhesive suitably employed in the medical sector for the connection of avariety of substances. Said material is an adhesive on acrylate basisthat can be hardened at wavelengths ranging between 320 and 380 nm.After hardening Permabond passes USP class VI tests. Permabond is alsoinsensitive to gamma radiation and a number of other sterilizationprocesses.

The severance elements designed to be quickly corrodible preferablyconsist of alloyed steel. In this connection, the stainless steel gradesof type AISI 301, 303 or 316 and/or subgroups of these types areparticularly preferred. Stainless steel material of this type preferablyhas a chromium content of between 12 and 20% w/w. Examples in this caseare steel grades 1.4410, 1.4310, 1.4301 and 1.4122. Suitable, forexample, are chromium-nickel steels of grade 18/8. The diameter of theseverance elements typically ranges between 0.01 and 0.05 mm.

To shorten the severance times even more the severance elements may bepre-corroded. Such a pre-corrosion may, for example, be achieved by heattreatment which causes the metal structure to be modified such that itvery quickly disintegrates in an electrolyte when an electric voltage isapplied. The heat treatment required for this can be carried out withthe help of a laser, in a customary furnace or by means of an inductioncoil. The temperature range required for this is approximately 500 to1000° C., preferably 600 to 950° C. and in particular 700 to 900° C. Itis assumed that such a heat treatment causes recrystallizationaccompanied by the formation of large microstructural grains and hardmetal carbides which results in the grain boundary stability todiminish. The formation of chromium carbides segregating at the grainboundaries leads to a chromium depletion of the matrix and furthermorebrings down the resistance to intergranular corrosion. This will quicklyenlarge the surface available for corrosion so that the structure willrapidly decompose within an electrolyte when a current has been applied.

Another possibility to design the severance elements so as to be wellcorrodible is to make use of material combinations for the relevantareas that are conducive to the formation of local elements. Examples inthis case are combinations of stainless steels with noble metals ornoble metal alloys, in particular platinum alloys.

The occlusion helixes proper are expediently made of platinum orplatinum alloys which have proven their worth. Especially preferred hereis the use of platinum-iridium alloys. The stabilization helixesconnected to the severance elements usually consist of alloyed steelmaterial, like the one used for the severance elements themselves,however, a platinum alloy similar to that employed for the occlusionhelixes may basically also be used for the stabilization helixes. Usingan alloyed steel material offers certain benefits in that theradiopacity between severance element and stabilization helix, on theone hand, and occlusion helix on the other increases. This is due to thefact that platinum alloys have a radiopaqueness that is by far higherthan that of steel alloys.

The insertion aid is preferably a customary guide wire of proven designfor the purpose of passing occlusion helixes through a catheter towardsa cavity to be occluded.

The device according to the invention may also be directly combined witha micro-catheter by means of which the occlusion helix is brought to theplacement site. The catheter used and the employed occlusion helix inthis case shall be matched with respect to their size. If necessary, thecatheter also may exert constraint on the occlusion helix as well assecuring means resulting in the occlusion helix to assume in theaneurysm its or the securing means' previously impressed secondarystructure not earlier than after it has been liberated and released fromsuch constraint. Expediently, the catheter is moreover provided withradiopaque markers enabling a placement in the target area with the aidof known imaging methods.

Aside from the device for the implantation of electrolytically severableocclusion helixes the invention furthermore relates to a correspondingmedical implant comprising at least one occlusion helix, at least oneseverance element and at least one stabilization helix, with thestabilization helix being arranged between severance element andocclusion helix so that the severance element and occlusion helix areindirectly connected in this manner, and with the stabilization helixbeing attached to the occlusion helix by means of an electricallyisolating adhesion layer.

Further elucidation of the invention is provided by way of examplesthrough the enclosed figures, where

FIG. 1 is a schematic representation showing the positioning of anocclusion helix in an aciniform aneurysm with the help of the inventivedevice;

FIG. 2 is a longitudinal section through the inventive device which incomparison to FIG. 1 is of significantly enlarged representation; and

FIG. 3 is a longitudinal section of the inventive device showing severalseverance elements.

FIG. 1 shows a vertical view of the occlusion helix 3 placed into anaciniform aneurysm 12. The occlusion helix 3 is moved distally withincatheter 1 with the help of the guide wire 4. When correctly positionedthe occlusion helix 3 exits from the end of catheter 1 and is introducedinto and fills up the cavity formed through the aciniform aneurysm 12.Within the aneurysm 12 the occlusion helix 3 forms secondary coils orturns which in particular can be caused by a stress- and/ortemperature-induced transformation from its martensitic to itsaustenitic phase of the occlusion helix 3 and/or securing means, whichhas not been shown here, inside the occlusion helix 3. Due to theformation of secondary coils or turns the aneurysm 12 is filled upparticularly effectively.

As soon as a certain length of the occlusion helix 3, which suits thevolume of the cavity to be filled, has been placed into the aneurysm 12the electrolytic separation is effected at the severance element 2. Forthis purpose, an electric voltage coming from voltage source 14 isapplied to severance element 2 with the severance element 2 serving asanode. The cathode 15 is positioned on the body surface. With the deviceaccording to the invention the electrolytic corrosion of severanceelement 2 occurs particularly quickly, within time spans usually wellbelow 1 min., i.e. within approx. 20 to 40 s (at 2 V, 2 mA). As per apreferred embodiment several severance elements 2 are provided withinthe area of the occlusion helix 3 so that the length of the occlusionhelix 3 introduced can be appropriately sized to suit the respectiveaneurysm 12.

In FIG. 2 the device according to the invention is shown schematicallyas a longitudinal section. The occlusion helix 3 shown in this figure isattached to severance element 2 by means of stabilization helix 5, saidlatter stabilization helix 5 being of smaller diameter than theocclusion helix 3 with the outside diameter of the stabilization helix 5basically coinciding with the inside diameter of the occlusion helix 3.Accordingly, the stabilization helix 5 can be inserted, at leastpartially, into the occlusion helix 3.

Stabilization helix 5 and occlusion helix 3 are interconnected via anadhesion layer 7, said adhesion layer 7 simultaneously isolating theocclusion helix 3 from the electric voltage applied to the severanceelement 2. In this manner, the current density in severance element 2 iskept at a particularly high level. An additional coating 11 applied tostabilization helix 5 serves to intensify this effect even more. Thecurrent applied with a view to separating the occlusion helix 3 can bepassed on to the severance element 2 via guide wire 4.

Additionally, a securing means 6 is arranged in the lumen of theocclusion helix 3, said means being a Nitinol wire which is providedwith an isolating coating or layer. This securing means 6 extends fromthe stabilization helix 5 to the distal end 8 of occlusion helix 3. Atthis point the securing means 6 is connected to the distal end 8 ofocclusion helix 3 with the aid of another isolating adhesive layer 9.Permabond is used for producing the adhesive layers 7 and 8 as well asthe coating of the stabilization helix 5.

For the purpose of producing the inventive device a stabilization helix5 is initially provided with a Permabond layer or coating followingwhich the securing means 6 designed as a Nitinol wire is welded to thestabilization helix 5 at location 10, i.e. at the distal end ofstabilization helix 5. Finally, the stabilization helix 5 is attached tothe occlusion helix 3 by means of Permabond.

FIG. 3 shows a device according to the invention having a plurality ofseverance elements 2. The device has been provided with a plurality ofocclusion helix segments 3 so that separation can be effected as desiredat different severance elements 2 to suit the size of the aneurysm to beoccluded. In this case, each severance element 2 is connected with therespective occlusion helix segment 3 via a stabilization helix 5 withsuch connection being made up according to the invention through theprovision of an electrically isolating adhesion layer. In addition, thestabilization helix 5 in this case is provided with coating 11 that alsohas electrically isolating characteristics.

Through the lumen of the relevant occlusion helix segments 3 extends ametallic securing means 6 which is provided with an electricallyisolating coating to safely isolate the securing means 6 from theocclusion helix 3. However, through the interior of securing means 6 anelectric current is passed on in distal direction to the relevantseverance element 2 where the electrolytic corrosion can be initiated asdesired and when necessary. Within an occlusion helix segment 3 themetallic securing means 6 extends in each case from the stabilizationhelix 5 which is proximally attached to the occlusion helix segment 3 tothe stabilization helix 5 distally connected to the occlusion helixsegment 3. In this way, the electric current is passed from oneseverance element 2 via stabilization helix 5 attached to it, thesecuring means 6 in distal direction to the subsequent stabilizationhelix 5 and on to the severance element 2 connected with it.Accordingly, securing means 6 is advantageously utilized in that it notonly provides increased safety in the event the occlusion helix 3 iswrongly placed but moreover serves to establish an electricallyconductive connection of the individual severance elements 2.

1. Device for the implantation of occlusion helixes (3) that can beseparated by electrolysis in blood vessels and body cavities, especiallyaneurysms (12), said device comprising an insertion aid (4), at leastone occlusion helix (3) that is distally arranged in relation to theinsertion aid (4) and at least one electrolytically corrodible severanceelement (2), with at least one stabilization helix (5) being arrangedbetween severance element (2) and occlusion helix (3), characterized inthat said stabilization helix (5) being connected with the occlusionhelix (3) by an electrically isolating adhesion layer (7) such that theocclusion helix (3) becomes isolated from the voltage when an electricalvoltage is applied to the severance element (2).
 2. The device accordingto claim 1, characterized in that the stabilization helix (5) isprovided with an electrically isolating coating (11).
 3. The deviceaccording to claim 1 or 2, characterized in that a securing means (6)extends through the lumen of the occlusion helix (3).
 4. The deviceaccording to claim 3, characterized in that the securing means (6)consists of a material having shape-memory properties.
 5. The deviceaccording to claim 4, characterized in that the securing means (6)undergoes transformation and assumes a previously impressed structurewhen placed into the blood vessel or body cavity.
 6. The deviceaccording to claim 4 or 5, characterized in that the securing means (6)consists of Nitinol.
 7. Device according to any one of the claims 3 to6, characterized in that at least one securing means (6) extends fromthe stabilization helix (5) to the distal front section (8) of theocclusion helix (3).
 8. Device according to claim 7, characterized inthat said at least one securing means (6) is connected with the distalfront section (8) of the occlusion helix (3) via an adhesion layer (9)which serves to isolate the occlusion helix (3) from an electricalvoltage applied to the severance element (2).
 9. The device according toany one of claims 3 to 8, characterized in that the securing means (6)is provided with an electrically isolating coating.
 10. The deviceaccording to any one of claims 3 to 9, characterized in that theocclusion helix (3) is provided at least on its inner side with anelectrically isolating coating.
 11. The device according to any one ofclaims 1 to 10, characterized in that the occlusion helix (3) isprovided with several spaced electrolytically corrodible severanceelements (2).
 12. The device according to any one of claims 1 to 10,characterized by several spaced occlusion helixes (3), with oneelectrolytically corrodible severance element (2) each being arrangedbetween the individual occlusion helixes (3).
 13. The device accordingto claim 11 or 12, characterized in that one securing means (6) each isarranged in the segments of the occlusion helix (3) located between theseverance elements (2) or in the individual occlusion helixes (3). 14.The device according to claim 13, characterized in that at least some ofthe securing means (6) in each case extend from one stabilization helix(5) connected by a severance element (2) to the next distally locatedstabilization helix (5).
 15. The device according to claim 13,characterized in that at least some of the securing means (6) extendfrom one severance element (2) to the next distally located severanceelement (2).
 16. The device according to any one of claims 11 to 15,characterized in that the severance elements (2) are connected with eachother so as to be electrically conductive via the securing means (6)extending through the lumen of the occlusion helixes (3).
 17. The deviceaccording to any one of claims 1 to 16, characterized in that theadhesion layers (7, 9) and/or the electrically isolating coatings (11)consist of an acrylate adhesive.
 18. The device according to claim 17,characterized in that the acrylate adhesive is Permabond.
 19. The deviceaccording to any one of the claims 1 to 18, characterized in that theseverance elements (2) are made of a steel alloy material.
 20. Thedevice according to any one of the claims 1 to 19, characterized in thatthe severance elements (2) are pre-corroded.
 21. The device accordingany one of claims 1 to 20, characterized in that the occlusion helixes(3) are made of platinum or a platinum alloy, in particular aplatinum-iridium alloy.
 22. The device according to any one of theclaims 1 to 21, characterized in that the insertion aid is a guide wire(4).
 23. The device according to any one of the claims 1 to 22,characterized in that said device is provided in the form of amicro-catheter (1).
 24. Medical implant according to any one of theaforesaid claims consisting of at least one occlusion helix (3), atleast one severance element (2) and at least one stabilization helix(5), with the stabilization helix (5) being arranged between severanceelement (2) and occlusion helix (3), and the stabilization helix (5)being attached to the occlusion helix (3) via an electrically isolatingadhesion layer (7).